DC Power Supply Components and Functions
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What is the primary function of a transformer in a DC power supply?

  • To step down AC voltage for desired DC output (correct)
  • To regulate the DC voltage
  • To rectify AC voltage to DC voltage
  • To filter the output voltage

    • What type of voltage is typically used in AC power supplies before converting to DC?

  • 50 V RMS
  • 330 V RMS
  • 220 V RMS (correct)
  • 110 V RMS

    • What component converts AC voltage to DC voltage in the power supply process?

  • Diode rectifier (correct)
  • Capacitor
  • Transformer
  • Regulator circuit

    • What is an ideal DC power supply characterized by?

    <p>Providing a constant output voltage regardless of input changes</p> Signup and view all the answers

    What distinguishes a real power supply from an ideal power supply?

    <p>Output voltage fluctuates with load or input changes</p> Signup and view all the answers

    How is line regulation defined in the context of voltage regulation?

    <p>Percentage change in output voltage for a given change in input voltage</p> Signup and view all the answers

    What component helps filter the full-wave rectified voltage in a DC power supply?

    <p>Capacitor</p> Signup and view all the answers

    What is the role of a voltage regulator in a DC power supply?

    <p>To provide a constant DC voltage despite changes</p> Signup and view all the answers

    What percentage of electronic equipment is powered from low voltage DC supplies?

    <p>95%</p> Signup and view all the answers

    What is one of the main characteristics required from a DC power supply?

    <p>Low noise characteristics</p> Signup and view all the answers

    What does the transformer in a DC power supply do?

    <p>Steps down AC voltage</p> Signup and view all the answers

    Which of the following is NOT a component of a DC power supply?

    <p>Amplifier</p> Signup and view all the answers

    What is the typical AC voltage connected to the transformer in a DC power supply?

    <p>220 V RMS</p> Signup and view all the answers

    Which type of voltage regulator converts AC mains into low voltage DC supplies?

    <p>Power supply converting AC mains</p> Signup and view all the answers

    What aspect does a well-regulated DC supply provide in response to load changes?

    <p>Fast response</p> Signup and view all the answers

    The main source of low voltage DC supplies can be which of the following?

    <p>Batteries</p> Signup and view all the answers

    What component serves as the control element in a series linear voltage regulator?

    <p>Pass transistor</p> Signup and view all the answers

    Which circuit configuration is utilized for sensing changes in output voltage in a series linear voltage regulator?

    <p>Output sample circuit</p> Signup and view all the answers

    In the process of regulation, what does the error detector compare?

    <p>Sample voltage and reference voltage</p> Signup and view all the answers

    What happens when a change is detected in the output voltage of a series linear voltage regulator?

    <p>The control element compensates the change</p> Signup and view all the answers

    Which circuit amplifies the error voltage between the reference and sensed values?

    <p>Op-amp circuit</p> Signup and view all the answers

    What type of regulated power supply uses series linear regulators?

    <p>Linear power supplies</p> Signup and view all the answers

    Which component does NOT typically function in a series linear voltage regulation circuit?

    <p>Current transformer</p> Signup and view all the answers

    What is the primary goal of a series linear voltage regulator?

    <p>To maintain a constant output voltage</p> Signup and view all the answers

    What does line regulation measure in a voltage regulator?

    <p>Percentage change in output voltage relative to input voltage changes</p> Signup and view all the answers

    What is the formula used to calculate line regulation?

    <p>(∆ Vout / Vout) * 100%</p> Signup and view all the answers

    If the output voltage decreases from 12 V to 11.9 V under full load, what is the load regulation percentage?

    <p>0.840%</p> Signup and view all the answers

    How is load regulation typically expressed?

    <p>As a percentage change from no-load to full-load</p> Signup and view all the answers

    A voltage regulator outputs 15 V but changes to 14.75 V under load. What is the line regulation percentage?

    <p>1.67%</p> Signup and view all the answers

    What does a drop in input voltage cause in a voltage regulator?

    <p>Decreased output voltage</p> Signup and view all the answers

    Which of the following best describes the relationship between load current and output voltage in load regulation?

    <p>Inversely proportional</p> Signup and view all the answers

    If the no-load output voltage is 10 V and the full-load output voltage is 9.5 V, what is the load regulation percentage?

    <p>5.26%</p> Signup and view all the answers

    What is the primary function of a zener diode in a Zener-regulated DC power supply?

    <p>To provide stable reference voltages</p> Signup and view all the answers

    How does the zener diode respond when the input voltage varies within its limits?

    <p>It maintains a nearly constant output voltage</p> Signup and view all the answers

    What happens to the zener current (IZ) as the input voltage (VIN) changes?

    <p>It changes proportionally to the input voltage</p> Signup and view all the answers

    What determines the limitations on input voltage variation in a zener-regulated power supply?

    <p>The minimum and maximum current values (IZK and IZM)</p> Signup and view all the answers

    In a Zener-regulated power supply, at what condition is the zener diode likely to operate efficiently?

    <p>Within the range of IZK to IZM</p> Signup and view all the answers

    What characterizes the output voltage across a zener diode at no-load conditions?

    <p>The output voltage remains stable</p> Signup and view all the answers

    Which of the following is NOT a feature of a Zener-regulated DC power supply?

    <p>It reduces output voltage ripple effectively</p> Signup and view all the answers

    When the load on a Zener-regulated power supply is at full load, what effect does it have on the zener diode?

    <p>The output voltage may drop below the regulated value</p> Signup and view all the answers

    What does the last two digits in the part number of a regulator in the 78XX series denote?

    <p>The output voltage of the regulator</p> Signup and view all the answers

    Which component is NOT typically included in an integrated circuit voltage regulator?

    <p>Output capacitor</p> Signup and view all the answers

    What type of voltage do the components in the 79XX series regulate?

    <p>Negative voltage</p> Signup and view all the answers

    Which of the following IC regulators is a variable voltage regulator?

    <p>LM317</p> Signup and view all the answers

    What is the primary function of an error detector in an integrated circuit voltage regulator?

    <p>To compare the output voltage to the reference voltage</p> Signup and view all the answers

    What type of load voltage regulation is typically achieved with an op-amp in a linear voltage regulator?

    <p>Amplified and constant load voltage</p> Signup and view all the answers

    In the 78XX series of voltage regulators, which of the following designs is used for fixed positive voltage outputs?

    <p>78xx</p> Signup and view all the answers

    What is the typical configuration for an integrated circuit voltage regulator with fixed negative output?

    <p>79XX series</p> Signup and view all the answers

    Study Notes

    ECE121: Electronics (1) - Lecture 1: Regulated Power Supply

    • The lecture covers regulated power supplies, a crucial component for most electronic equipment (approximately 95%).
    • Power sources can be batteries or AC mains-to-DC converters.
    • Electronic components need regulated DC supplies, characterized by stable voltage, minimal noise, and rapid response to load changes.
    • A typical DC power supply's components include a transformer, rectifier, filter, and an IC regulator, in that order.
    • The transformer steps down the AC voltage (typically 220 V RMS) to the desired DC output level.
    • The rectifier converts the AC voltage to a pulsating DC voltage using diodes (full-wave rectification).
    • A filter, usually a capacitor, smooths the pulsating DC voltage to produce near-constant DC voltage.
    • A regulator circuit ensures a stable output voltage, despite input voltage or load changes.
    • Ideal power supplies maintain a constant output voltage, regardless of changes in input voltage or load.
    • Real power supplies' output voltage changes with load or input changes.

    Concept of Voltage Regulation

    • Line regulation measures the percentage change in output voltage due to an input voltage change.
    • It's calculated as [(ΔVout/Vout) * 100%]/ΔVin, with percentage change per volt as the unit (e.g., %/V).

    A Zener-Regulated DC Power Supply

    • A zener diode creates a stable reference voltage.
    • Output voltage remains nearly constant as input voltage varies, within defined limits.
    • Output current (Iz) changes proportionally to input voltage changes.
    • Minimum and maximum current values (Izk, Izm) dictate input voltage variations.

    Basic Linear Voltage Regulator

    • Regulated power supplies include linear power supplies (series and shunt) and switched power supplies.
    • The control element in a series linear regulator is a pass transistor.
    • Sample circuit measures output voltage.
    • Error detector compares sample and reference voltages.
    • Compensating actions maintain output voltage stability by the control element.
    • Resistor voltage divider detects output voltage changes, amplified by the op-amp.
    • The op-amp adjusts the transistor to keep output voltage to the reference value.

    Integrated Circuit Voltage Regulators

    • IC regulators combine reference voltage, error detection, and control components in one unit, optimizing efficiency.
    • 78xx series are fixed positive voltage regulators (e.g., 7805 is 5V).
    • 79xx series are fixed negative voltage regulators (e.g., 7905 is -5V).
    • LM317 is a variable positive voltage regulator.
    • LM337 is a variable negative voltage regulator.
    • The last two digits in the IC regulator part numbers correspond to output voltage.

    Power Supply Project

    • Students should choose a type of IC regulator, simulate it using Proteus software, and submit their results by a specified date.
    • Teams should create variable (+ve or -ve) power supplies and deliver them by another specified date.

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    Related Documents

    ECE121 Electronics (1) Lecture 1 - Regulated Power Supply PDF

    Description

    This quiz assesses your knowledge of the components and functions involved in DC power supplies. Topics include transformers, rectifiers, voltage regulation, and the characteristics of ideal versus real power supplies. Test your understanding of how AC voltage is converted to DC and the roles of various components in the process.

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